Oil well cementing plug



' April 16, 1940.,

t F. MAINES 2,197,396

OIL WELL CEMENTING PLUG I Filed Dec. 29, 1957 Q Patented Apia 16, 1940UNITED STATES PATEN OFFICE;

. on. WELL CEMENTING m. Fred Maines, Long Beach, Calif;

Application December 29, 1937, Serial No. 182,195

Claims.

10 and to provide a construction that will be effective in producingimproved and beneficial resuits in the cementing operations,particularly the keeping of the cement and fiuidentirely separate fromeach other while the cement is being 1' forced downwardly through-thecasing, and until such time as it is discharged from the lower end ofthe casing into the well hole, and further, to provide the lower one ofthe plugs which has a passageway to permit the cement to dischargedownwardly through the plug, with a barrier that normally prevents theflow of cement downward ly through the plug, but which barrier may beruptured or broken under a predetermined degree of pressure applied tothe cement by the pump 25 at the top of the well while the bottom plugrests on the float-shoe or other obstruction at the lower end of thecasing.

A further object of my invention is to provide well cementing plugs ofthe character referred to that will'cooperate so as to enable the cementto be conveniently and economically delivered through the casing to thepoint where the cementing of the well is to be accomplished, and thecement then being forced under pressure through the lower one of theplugs and the float-shoe that is carried by the lower end of the casinginto the annular space within the well hole around the casing so as toprovide a concrete wall surrounding the well hole throughout the areathroughwhich water flow or seepage would otherwise occur.

With the foregoing and other objects in view, my invention consists incertain novel features a of construction and arrangements oi parts thatwill be hereinafter more fully described and claimed and illustrated inthe accompanying drawing in which:

Fig. 1 is a vertical section taken through the 50 lower portion of awell hole, with the casing positioned therein and showing nrv improvedcementing plugs positioned within said casing and with the lower plugresting on the float-shoe that is carried by the lower end of thecasing.

Fig. 2 is a side elevational view partk in section, oi! a modified formof the upper one of the plugs.

Fig. 3 is a detail section taken through the upper portion of a modifiedform of the lower plug.

Fig. 4 is a vertical section taken through the 5 lower portion of amodified form of the'upper plug and also the upper portion of a modifiedform of the lower plug.

Referring by numerals to the accompanying drawing which illustratesa.preferred embodil0 ment of my invention, It designates the well casingthat occupies the well holel W, the lower end of the casing beingdetachably connected to a conventional float-shoe S provided with theusual axial opening 0.,

The lower plug, designated by the numeral II,

is substantially cylindrical in form and con-- structed of. wood, metal,rubber or composition.

The diameter of this plug is slightly less than the internal diameter ofthe well casing, and the length of the plug issomewhat greater than itsdiameter. The lowerend of the plug I l is slightly tapered, asdesignated by I2, in order to permit the marginal portion of the packingdisc,

- carried by the lower end of the plug to flex up wardiy as a result ofcontact with the wall of the casing as the plug passes downwardly there'through, and extending axially through the plug .is a bore or opening13.

Secured in any suitable manner to the under face of the plug l I is apacking disc I! preferably formed of flexible or semi-flexible material,for instance leather or composition, and the edges of this discareadapted to engage the inner face of the casing as the plug movesdownwardly therethrough.

Formed in the center of this packing disc is an aperture I! thatcoincides withthe axial bore or opening it through plug ll.

' Overlying the upper end of plug II is a section or sections it of thinmaterial, preferably heavy fabric such as canvas, or thismember may beleather, composition, or in some instances thin sheet metal such as tin,aluminum, copper or the like. I Instead of utilizing a barrier offabric, leather, sheet metal or the like, the barrier may take the formof a valve having means associated with it to normally maintain it inclosed Position, and

which will open only under a predetermined degree of pressure.

Overlying this member I6 is a packing disc I! that is practicallyidentical with the disc I, and

being formed of flexible or semi-flexible material L such as leather orcomposition, and the edge of this disc engages the inner face of thecasing as the lower plug moves downwardly there- -through.,

Formed in the center of packing disc I! is an I aperture 18 thatcoincides with the axial bore ii in plug I l. Suitably secured camp ofthe packing disc I! is a disc Is that is somewhat smaller in diameterthan the packing I], said disc is being preferably formed of wood, metalcom- 10 position or the like, and having formed through its center anaperture II that coincides with the -aperture iii in packing member l1and the bore l3throughplug ll.

The upper plug, designated by numeral 2|, com- 1s prises a solidcylindrical body preferably formed Applied to the under face ofthe lowerone of the packing members 23 and concentric therewith is a ring 24 ofwood, metal, composition or so the like, and which is securely fastenedto the lower end of the plug.

Suitably secured to the upper end of plug 'II and overlying theintermediate portion of the upper packing member 23 is a concentricallyar- 35 ranged disc 25 that is slightly smaller in diameter than saidupper packingmember, and thus only the marginal portion of the upperpacking member functions to close and pack the joint between. the upperend of the plug and the inner face of a the casing.

In Fig. 2 I have illustratedakmodifled form of upper plug 2|, and insuch construction the rin 24 at the bottom of the plug and the disc 25at the upper end thereof are eliminated and the 4s packing members 23are secured to the end faces of the plug by fastening devices such asnails, screws or the like. In the modified'construction illustrated inFig. 3, the perforated disc 20 is eliminated and the so flexible memberi1 is secured directly to the upper end of the plug H by nails, screwsor the like, and said disc overlying the member It.

In the modified construction illustrated in Pig. 4, the disc l9 that isapplied to the upper end of 55 the lower plug l I is provided with acentrally arranged tapered aperture 2 6 that functions as a seat for atapered plug 21; which'latter projects from the lower end of the upperplug 2|.

In the use of my improved cementing plugs,

go plug H is placed in the upper end of the casing and cement is pumpedinto the casing on top of said plug, with the result that the plug andcement are forced downwardly through the casing and all mud and liquidin front of or below as the plug will be forced downwardly through theswing and discharge through the lower end thereof through opening 0 infloat-shoe B. This mud and liquid will be forced upwardly through theannular space surrounding the lower 70 portion of the casing. After therequired amoimt of cement has been delivered into the casing, the upperplug 2! is placed in the casing on top of the cement and mud or liquidis now pumped into the casing above the upper plug 2i, thus forcing anthe two plugs with the interposed body of cement aromas downwardLvthrough the casing until the lower end of the lower plug rests on thefloat-shoe or other obstruction.

During this downward movement of the plugs and cement, the packingmembers M and i1 5,

scrape the inner surface of the casing thereby removing practically allmudthat might otherwise adhere thereto, and the packing members 28carried by the upper plug scrape the inner surface of the casing toremove any cement that 10 might adhere thereto.

During the downward travel of the plugs and interposed body of cementthrough the casing, the member I. functions as a barrier to eifectlvelyprevent the cement between the plugs from is do wardly through the,lower plug and mixing wi the mud and liquid below said lower Plug.

when the lower plug ll rests upon the floatshoe or other obstruction,such condition will be indicated on the pressure gauge of the pump andthe operation of the pump is continued to build up pressure in the mudor fluid in the casing above the upper plug: and when a predetermineddegree of pressure has been delivered that portion 1 oi the member I!that closes the upper end ofopenlng il in the lower plug will beruptured, thereby bringing about a drop in the pressure which conditionwill show on the pressure gauge associated with the pump and thusthepump 0 operator will know that the member It has been ruptured so as topermit the cement to pass downwardly through-the opening inthe'floatshoe.

Continued operation of the pump develops sufflcient pressure to expelsaid cement through the opening it in the lower plug and through'theopening in the float-shoe. and this cement will be forced upwardlythrough the annular space surroimdlng the casing, and which actionelevates 40 the mud and liquid previously'expelled from the lowerportion of the casing and thus provides a cement wall around the casingthat keeps water from seeping into the protected'portion of the wellhole. A

As the cement is forced upwardly in the well hole around the'casing anddrives the mud or fluid upwardly, a practically definite separation ofthe cement, mud and fluid is produced and maintained, due to thedifference in the specific I0 gravities of the mud or fluid and thecement, the latter being considerably heavier than the mud or fluid. n

An especial advantage of my improved cementing plugs is that the memberIi that is carried by II the lower plug forms a barrier that keeps thecement pumped into the casing, entirely separate from the mud or waterbelow the plug and within the well hole "surrounding the casing. 1

Obviously, the barrier member it may be iormedof any material that willrupture under a predetermined degree of pressure and as a result, theplugs may be used under any and all condi- 'tions regardless of thedepth at which the cementing-off job is accomplished, and likewiseregard- 9s less of the amount of cement required for accomplishins thedesired results.

As a valve is used in the place of the barrier Ii, said valve may be ofthe type that is normally held in closed position by a. spring, andwhich (0 latter is of such size and tension as to yield only under apredetermined pressure. a

when all of the cement has been expelled. through the lower plug, thelower end of the upper plugor the ring 24 carried thereby will rest 1;

directly on top of the lower plug or the disc I9 carried thereby, thusproviding a fluid-pressure tight joint between the two plugs and thejoints between the ends of both plugs and the casing are sealed by thepacking members I4, l1 and 23 that are carried by the ends of the plugs.

Where the modified construction illustrated in Fig. 4 is provided, thetapered member 2'! that effective in performing the functions for whichit is intended.

It will be understood that minor changes in the size, form andconstruction of the various parts i of my improved oil well cementingplugs may be made and substituted for those herein shown and describedwithout departing from the spirit of my invention, the scope of which isset forth in the appended claims. i

I claim as my invention: 1. A well cementing plug provided with a pas- Isageway for mud, fluid and cement, a member normally closingsaidpassageway and adapted to rupture under predetermined degrees ofpressure, and a packing disc carried by said plug.

2. A well cementing plug provided with a passageway for mud, fluid andcement, a member normally closing said passageway and adapted to ruptureunder predetermined degrees of pressure and packing discs carried by theends of said plug.

3. In an oil well cementing means, the combination witha cementing plugand packing members carried by the ends thereof of a second plugprovided with an axial opening, a rupturable' member closing saidopening and packing members carried by the ends of said second mentionedp ug.

4. An oil well cementing pl having an axial opening, packing memberscarried by the ends plug having a passageway for-mud, liquid and cement,a rupturable member closing saidpassage'way and capable of beingruptured under predetermined degrees of pressure, a plate secured to theplug and overlying said member, said plate having an aperture thatcoincides with'the passageway'in the plug and a member projecting fromone end thereof and adapted to'enter and close the aperture in the platethat'is carried b the first mentioned plug.

6. A cementing plug provided with an axial duct for the passage of mud,liquid and cement, means normally closing said duct and adapted torupture under a predetermined degree of pressure and a member overlyingsaid duct-closing means and provided with an aperture that registerswith the duct through said plug.

'7. A cementing plug provided with an. axial duct for the passage ofmud, liquid and cement, means secured to one end of said plug for normally closing said duct and adapted to rupture under a predetermineddegree of pressure and means carried by said plug for packing the jointbetween said plug and the casing in which said plug is positioned;

8. The combination with a cementing plug having aduct for the passage ofmud, liquid and cement and means normally closing said duct and adaptedto rupture under a predetermined degree of pressure, of a second plugadapted to be positioned'in the well casing above the first-mentionedplug.

9. The combination with a cementing plug having a duct for the passageof mud, liquid and cement and means normally closingsaid duct andadapted to open under a predetermined degree of pressure,.of a secondplug adapted to be vpositionedlin a well casing above thefirst-mentioned plug and means for packing the joints between said plugsand the casing in which they are positioned.-

10. The combination with a cementing plug having a duct for the passageof mud, liquid and cement and means normally closing said duct andadapted to open under a predetermined degree of pressure, of a secondplug adapted to be positioned in a well casing abovethe first-mentionedplug, means for packing the joints between said plugs and the casing inwhich they are positioned and means for producing a fluid pressure tightjoint between the upper end of the lower plug andthe lower end of theupper plug.

FRED MAINES.

